Concentrated solar power (CSP, also known as “concentrating solar power”) technology uses sunlight directed at heat transfer fluids that heat up and whose thermal energy is then transferred (e.g., for heating) or turned into electrical power (e.g., by use of a turbine generator). Conventional CSP reflectors are made with silver coated glass, which currently reflect approximately 94 percent of the solar spectrum. Such CSP reflectors are relatively expensive, heavy, and fragile.
CSP systems typically use lenses or reflectors and tracking systems to focus a large area of sunlight into a small beam. The concentrated sunlight is then used as a heat source for a conventional power plant (e.g., a steam driven turbine generator). A wide range of concentrating technologies exists; the most developed are the solar trough, parabolic dish and solar power tower.
Solar troughs are the most widely deployed and the most cost-effective CSP technology. A solar trough consists of a linear parabolic reflector that concentrates sunlight onto a receiver positioned along the reflector's focal line. The reflector is made to follow the sun during the daylight hours by tracking along a single axis.
A parabolic dish system consists of a stand-alone parabolic reflector that concentrates sunlight onto a receiver positioned at the reflector's focal point. The reflector tracks the sun along two axes. Parabolic dish systems give the highest efficiency among CSP technologies. Power towers are less advanced than trough systems but offer higher solar concentration ratios (e.g., in excess of 1000 times more) and better energy storage capability.